Note 15 - Share Plans (Tables)

12 Months Ended

Dec. 31, 2016

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	201 6			201 5			201 4
Weighted average grant date fair value	$	13.77		$	19.07		$	26.35
Assumptions:
Expected stock price volatility		41	%		41	%		45	%
Risk free interest rate		1.31	%		1.72	%		1.90	%
Expected annual dividend per share	$	-		$	-		$	-
Expected life of options (years)		6.25			6.25			6.25

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value ($ in thousands)
Outstanding as of December 31, 2013		2,937,301		$	5.74		9.5	$	148,369
Granted		187,189			57.21
Exercised		(549,282	)		3.44
Expired		(259	)		15.94
Forfeited		(32,810	)		12.68
Outstanding as of December 31, 2014		2,542,139			9.94		8.5	$	96,518
Granted		287,165			45.18
Exercised		(604,088	)		3.79
Expired		(6,409	)		50.11
Forfeited		(90,793	)		37.27
Outstanding as of December 31, 2015		2,128,014			15.15		7.7	$	40,271
Granted		398,313			33.24
Exercised		(995,469	)		2.89
Forfeited		(47,894	)		37.41
Outstanding as of December 31, 2016		1,482,964			27.49		7.5	$	23,840
Exercisable as of December 31, 2016		787,654			17.64		6.7	$	19,897

Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

	Shares			Weighted- Average Grant- Date Fair Value
Non-vested as of December 31, 2013		304,406		$	29.68
Granted		115,473			54.35
Vested		(105,123	)		28.31
Forfeited		(47,472	)		42.31
Non-vested as of December 31, 2014		267,284			38.72
Granted		193,117			41.31
Vested		(183,362	)		32.56
Forfeited		(33,999	)		47.77
Non-vested as of December 31, 2015		243,040			44.16
Granted		232,295			33.56
Vested		(95,858	)		41.93
Forfeited		(18,074	)		38.30
Non-vested as of December 31, 2016		361,403			38.18